Heat transfer system



Jan. 7, 1958 J. A. WHITE HEAT TRANSFER SYSTEM 2 Sheets-Sheet 1 Filed Feb. 17, 1955 as vmvmwl INVENTOR. JOHN A. WHITE ATTORNEY? Jan. 7, 1958 J. A. WHITE HEAT TRANSFER SYSTEM Filed Feb. 17, 1955 2 Sheets-Sheet 2 INVENTOR. JOHN A. WHITE A T TORNE X United States Patent-G HEAT TRANSFER SYSTEM John A. White, Yonkers, N. Y., assignor to General Precision Laboratory Incorporated, a corporation of New York Application February 17, 1955, Serial No. 488,748

2 Claims. (Cl. 174-16) This invention relates to heat transfer systems containing heat exchangers, and particularly to such systems employed for cooling apparatus having energy losses dissipated as heat.

This invention is particularly useful in aircraft designed for high altitude operation and having pressurized spaces. When this invention is employed in such aircraft the cold rarefied air of 'high altitudes may be used for cooling the apparatus while permitting operation in a hermetically sealed case containing a gaseous filling at relatively high pressure. The hermetically sealed case may be in turn positioned in a space containing air which can be at any pressure and at any temperature ranging from much colder than the desired apparatus temperature to much hotter, without preventing adequate cooling of the apparatus.

An object of this invention is to provide an improved, readily assembled construction for housing apparatus, wherein the apparatus may be hermetically sealed yet readily made available for servicing when necessary.

Another object of the invention is to provide compact mounting and housing devices for electronic apparatus which may be hermetically sealed yet cooled by the introduction of a coolant fluid, wherein the circuit components are substantially shielded from external electrical interference. Still another object of the invention is to cool apparatus by means of fluid coolant kept from contact with the apparatus and at a separate pressure, the envelope of the apparatus being surrounded by an atmosphere which may be different in temperature and pressure from those of both the coolant and the apparatus.

This invention employs a heat exchanger with two separate sets of fluid ducts. This heat exchanger also serves as a mechanical core supporting the apparatus to be cooled. The apparatus secured to this core is surrounded by a hermetically sealed case or envelope which also provides mechanical protection and may serve as an electrostatic shield. A small motor circulates fluid around the apparatus and through one set of heat exchanger ducts in a closed fluid path wholly within the hermetically sealed case. A second set of fluid ducts of the heat exchanger is connected to ingress and egress pipes which pass through the walls of the hermetically sealed case. When the invention is employed in an aircraft these pipes may be connected for circulation of cooling air through the second set of duct-s, the air being taken from outside the aircraft or elsewhere.

By using this construction rarefied cold air may be used for cooling while high pressure dried air is recirculated through the apparatus. When the apparatus is electrical this is an important feature since it prevents dirty or humid air from coming in contact with the apparatus. The temperature of the air surrounding the case has negligible effect on the apparatus temperature because neither the apparatus nor the heat exchanger is in effective conductive contact with the case.

Further understanding of this invention may be secured from the detailed description and associated drawings, in which:

Figure 1 depicts the complete assembly of an electronic instrument, with the case drawn ofi, employing the heat transfer system of this invention.

Figure 2 is a view of the base and heat exchanger used in connection with the invention.

Figure 3 depicts a detail of the interior of the heat exchanger.

Figure 4 is a side view of the heat exchanger.

Figure 5 is a section taken on the line 55 of Fig. 4.

Figure 6 is a rear view of the heat exchanger.

Figure 7 is a side view of the frame used in connection with the invention.

Figure 8 is a rear view of the frame enclosing the heat exchanger.

Figure 9 depicts the bulkhead used in connection with the invention.

Referring now to Fig. 1, a base or end plate 11 serves as the fundamental construction element of the device of the invention. To this plate the heat exchanger 12, Fig. 2, is secured by means of its terminal pipes 13 and 14 and associated flanges 16 and 17. The cylindrical case 18, Fig. 1, is also secured to the base 11 by a hermetic seal at the edge 19.

The heat exchanger 12 is made of seven thin elements, all alike and each constructed as indicated in the cross section of Fig. 3. Each element consists of two thin metal side plates 21 and 22, with a single thin metallic sheet 23 repeatedly folded between them and welded to the side plates at each fold as at welds 24 and 26. The element thus forms a cellular sandwich containing many tiny parallel air passages between two opposite edges. These opposite edges or sides are indicated by the dashed lines 27 and 28, Fig. 4, depicting the top and bottom terminating surfaces of all of the cellular air passages of the seven elements. Four of the seven sandwich elements form the air path between the pipe terminals 13 and 14. These four elements 29, 31, 32, and 33, Fig. 5, are each provided with four metallic sheet deflectors so that air passing vertically up through the cellular passages is deflected toward the exit pipe 14. These four deflectors are indicated by the dashed lines 34, 36, 37 and 38, Fig. 4, their end edges being visible in Fig. 5. Similar deflectors 39, 41, 42 and 43 guide air from pipe terminal 13 into the bottoms of the four elements. Three other sandwich elements 44, 46 and 47, are interleaved between elements 29, 31, 32 and 33 as indicated in Fig. 5. They are similarly provided with top and bottom deflectors 48, 49, 51, 52, 53, 54, 56 and 57, Fig. 4. The upper ends of the passages of elements 44, 46 and 47 terminate in a rectangular pipe opening 58, Figs. 4 and 6, while the lower ends of the same passages terminate in the open rectangular area 59, Fig. 4.

In the operation of this exchanger the counterflow principle is employed. The pipe terminal 13 serves as the input for externally-provided cooling air. This air is deflected by deflectors 39, 41, 42 and 43 into the lower ends of the several thousands of cellular passages in elements 29, 31, 32 and 33, Fig. 5. The air passes vertically upward as indicated by arrows 61, Fig. 4, and out pipe terminal 14. A second completely separate set of air paths start-s at the rectangular pipe opening 58. The air is deflected by deflectors 48, 49, 51 and 52 into the vertical cellular passages of elements 44, 46 and 47, Fig. 5, and passes downward as indicated by arrows 62, Fig. 4, until it is deflected by deflectors 53, 54, 56 and 57 and is exhausted out the opening 59.

A frame 75, Figs. 7 and 8, has the general shape of a rectangular box of four sides with open ends. Its dimensions are such as to fit around the heat exchanger 12, Fig. 4, leaving a space of about 33 inch on all four sides,

3 as indicated in Fig. 8. The front edge 63 of the frame is designed to be secured to the inside surface 64, Fig. 4, of the base 11. Two cutouts 65 provide connection between the interwall space and the surrounding space.

A bulkhead 69, Fig. 9, has a circular perimeter fitting the inside of case 18, Fig. 1. It is secured to the rear side 60, Fig. 4, of the heat exchanger, indicated by dashed lines 66, Fig. 9, and to the rear end 70, Fig. 7 of the frame as indicated by dashed line 67, Fig. 9. The bulkhead thus hermetically seals the space between heat exchanger and frame at the rear. A rectangular opening 68 fits around the rectangular pipe terminal 58, Figs. 4 and 6. The bulkhead 69 is visible in Fig. 1. A motor 71 and a blower 72 are secured to bulkhead 69 and the blower outlet is connected through a hose to the rectangular opening 58, Fig. 4, of the heat exchanger.

Numerous electronic and electrical components are secured to the frame and to the bulkhead. Some cmponents are secured to the frame brackets 73 and 74, Fig. 7, and others to numerous other brackets and details which have been omitted to clarify the description but which are depicted or inferred in Fig. 1. This type of construction provides accessibility and facilitates testing and subassembly replacement. All components and even the complete external cooling system may be operated with the case removed, as the case forms no part of the external cooling system and plays no part in its cooling action.

In the operation of the device of this invention let it be supposed that the apparatus is installed in a pressurized compartment of a high altitude airplane. Cooling air may be taken from outside the airplane so that when the airplane is at a high altitude the cooling air pressure will be low being, for example, at a pressure of one pound per square inch absolute at an altitude of 62,000 feet. However, it is not necessary to use external chilled air for external cooling. The warm air vented from the passenger cabin may be used for cooling even though its temperature may be as high as 131 F. Its pressure will be between 10 and 14.7 lbs. per sq. in. abs. In one design the internal hottest spot temperature was held to +185 F. when +131 F. air was used for cooling, and when the air ambient around the cover 18 had a temperature of +250 F.

The path of the external cooling air passed into the pipe terminal 13, Fig. 4, is as shown by the arrows 61, passing through the numerous cellular passages of the elements 29, 31, 32 and 33, Fig. 5, and out pipe terminal 14 to an external exhaust point. The path of the internal cooling air is from the blower 72, Fig. 1, through its hose connection to the rectangular pipe opening 58, Fig. 4, through the numerous cellular openings in elements 44, 46 and 47, Fig. 5, as schematically indicated by arrows 62, Fig. 4, out opening 59, through the V inch spaces 76, between the frame 75 and heat exchanger 12, Fig. 8, to the front of the frame, and through the two openings 65, Fig. 7, to the space between frame and case occupied by the electronic apparatus. The air then finds its way toward the rear through, around and over the electronic apparatus to the bulkhead, Fig. 9, and flows through the holes such as holes 77 and 78 provided therein for the purpose. The air then passes over and around apparatus fastened to the rear surface of the bulkhead and finally enters the intake of blower 72, Fig. 1, and is recirculated.

What is claimed is:

1. A heat transfer system comprising, a base, a heat exchanger including two sets of ducts positioned in heat exchanging relationship but hermetically isolated from each other secured to said base, an apparatus frame enveloping said heat exchanger and secured thereto, electronic apparatus being capable of energy loss and of emitting loss energy as heat, said electronic apparatus containing interstices and spacers for the transmission of cooling gases, an enveloping case removably hermetically sealed to said base hermetically sealing said apparatus from the ambient atmosphere, means externally forcing cooling gas through orifices in said base into, through and out of one set of ducts in said heat exchanger, said one set of ducts being hermetically isolated from the interior of said enveloping case, an air blower secured to said apparatus frame recirculating an internal cooling gas inside said enveloping case through another set of ducts of said heat exchanger and through the interstices and spaces of said electronic apparatus.

2. A heat transfer system for electronic apparatus comprising, a heat exchanger unit including two sets of ducts positioned in heat exchanging relationship but hermetically isolated from each other, an enclosure member closely surrounding but spaced from said heat exchanger unit providing a fluid passageway between the exterior walls of said heat exchanger unit and the interior walls of said enclosure member, a base plate sealed to one end of said heat exchanger unit and said enclosure member, a blower carried by said base plate and positioned in fluid conducting relationship with the inlet of one of said sets of ducts, the outlet of said one set of ducts being in fluid communication with the fluid passageway between the walls of said heat exchanger unit and said enclosure member, fluid ports in the walls of said enclosure member at the end opposite to said base plate, means for attaching heat emissive electronic apparatus to said enclosure member, said heat exchanger unit, enclosure member, electronic apparatus, base plate and blower being contained within a casing hermetically sealed from the surrounding atmosphere, and inlet and outlet ducts in said casing communicating with the other of said set of ducts.

References Cited in the file of this patent UNITED STATES PATENTS 1,811,455 Cook June 23, 1931 2,445,582 Melville July 20, 1948 2,654,583 Treanor Oct. 6, 1953 FOREIGN PATENTS 246,358 Switzerland Sept. 16, 1947 

